Finely chop the onion and garlic. Roughly chop the carrot then the broccoli and cauliflower.
Heat the oil in saucepan over medium heat. Gently sauté the onion for about 5 minutes, until softened. Add the garlic and cook for another minute, then add the carrot, broccoli & cauliflower, and sauté for another 5 minutes.
Add the stock and bay leaf, bring to a boil, then simmer for 15 minutes over low heat, or until the veggies are tender.
Remove the pot from the heat, discard the bay leaf, then add the parsley leaves and a spoonful of cider vinegar.
Using a stick blender, pulse until you get a smooth soup.
Taste and adjust the seasoning and vinegar. Add more stock if it’s too thick.
Serve warm.